Passenger cars with folding seats have represented the state of the art for many years. In several models the backrest is divided into sections so that certain segments or the entire backrest may be folded down. The arresting and securing of the backrest and/or portions thereof is facilitated by a locking mechanism, which can be released by use of an actuating knob connected to mechanical transmission means such as a cable, rod or lever. The backrest or a portion thereof can be folded forward and down to expand cargo area. The backrest can then be folded back to return the seat to passenger use. When returning the seat to passenger use, it can occur that the backrest does not engage the locking mechanism completely or at all, even though the user may be convinced upon visual examination that the backrest is properly locked. Only by pulling on the backrest can it be determined with absolute certainty whether the backrest is in a properly locked position. However, for reasons of convenience this test is frequently not performed. A backrest that is not properly locked, however, can become a fatal hazard for passengers, since a rear-end collision or heavy breaking can cause objects stored in the cargo space to enter into the passenger cabin like projectiles.
To prevent this from occurring, indicator devices have been developed that signal to the driver that the backrest of a backseat is not locked or not locked properly.
DE 102 30 637 A1 describes such a display device. The device includes an illuminating device, which signals through illumination whenever a backrest is not locked. In addition to the signal device, an actuating element of the display indicating an unlocked backrest is also provided. In locked position, the upper end of the actuating element is flush with a frame provided on the upper face of the backrest. To unlock the backrest, the actuating element is pulled upward. In this state, the actuating element projects above the upper face of the backrest and remains in this position when the backrest is unlocked.
A display of the same type for indicating that a vehicle seat backrest is not in locked position is described in JP 2001097009-A. In this commonly known solution, a separate indicator for signaling that the backrest is not in locked position is provided in addition to the actuation knob.